Traumatic brain injury (TBI) is a problem of great concern for the
veteran population, and the Department of Veteran Affairs (VA) has
devoted significant healthcare resources to the rehabilitation of
veterans with TBI. Evaluating the outcomes of these rehabilitation
activities requires measuring whether they improve veterans' lives
in a meaningful way, with specific focus on improving the ability of
veterans with TBI to join in normal work and community activities. This
type of social activity is referred to as "participation";
participation in work and community activities is strongly linked to
perceived quality of life. This article considers issues related to
improving the measurement of social participation in veterans with TBI
to help improve the meaningful evaluation of rehabilitation efforts.

TBI is an injury that disrupts the normal function of the brain.
TBI severity may range from mild (a brief change in mental status or
consciousness) to severe (an extended period of unconsciousness or
amnesia after the injury) [1]. TBI is often classified as either closed
or penetrating and may result from a number of different types of
events, including sudden acceleration or deceleration of the head (e.g.,
motor vehicle accident or fall), penetrating injury (e.g., gunshot
wound), or blast injury (e.g., explosion). TBI of all types can result
in the immediate rupture of cellular and vascular membranes with
impaired cerebral blood flow followed by necrotic and apoptotic cell
death and with subsequent hypoxia, hypotension, and increased
intracranial pressure [2]. Newer imaging techniques have indicated that
cytoskeletal damage may contribute to diffuse axonal injuries that
disrupt nerve cell and network functioning [2]. However, understanding
that all types of TBI can and often do co-occur with multiple other
injuries, including significant cardiopulmonary, burn, or
musculoskeletal injuries and posttraumatic stress disorder (PTSD), is
important [2-3]. This is especially true with TBI in a combat
environment. Mild TBI and PTSD present diagnostic challenges because
symptoms may overlap, and the entire constellation of injuries
complicate and compound each other.

Population-based epidemiological studies in the U.S. civilian
population provide insights into the magnitude of TBI in the United
States. The annual incidence of U.S. civilians with TBI is estimated to
range from 0.4 to 0.8 percent [1-2], or 1.2 million to 2.4 million
persons experiencing TBI each year. A 2010 Centers for Disease Control
and Prevention report identified 1.7 million U.S. civilians incurring a
TBI each year, with 80 percent of these being treated and released from
hospital emergency departments, 16 percent hospitalized, and 3 percent
fatalities [4].

Although no population-based epidemiological studies stratify
incidence and prevalence data by TBI severity in veteran and military
populations, some data provide insight into the occurrence of TBI for
these groups. Estimates of the number of veterans and military
servicemembers with TBI vary widely according to the data sources and
research methods employed in a given analysis. According to the
Department of Defense, about 35,000 servicemembers have been wounded in
action as of 2009 [5], or about 2 percent of the 1.6 million
servicemembers who have served or are serving in Operation Iraqi Freedom
and Operation Enduring Freedom over the past decade. However, some
researchers have suggested that perhaps around 70,000 of these 1.6
million servicemembers (4%) have sustained a TBI [6], while others have
suggested much higher numbers, perhaps as many as 320,000 (20%) [7-9].
These estimates of the magnitude of possible TBI in military personnel
range from approximately 2 to 10 times greater than the total number of
servicemembers identified as wounded in action, and therefore include
individuals who were not officially identified as wounded during their
tour of duty. Injuries not initially recognized during tour of duty
would almost exclusively be expected to be mild injuries.

While the data regarding the magnitude of mild TBI in military
servicemembers and veterans are very concerning, it is also important to
recognize that mild TBI and what is sometimes called
"postconcussive disorder" have poor diagnostic reliability and
validity. Many postconcussive symptoms such as headache, sleep
disturbance, and difficulty concentrating have a base rate in the
general nondisabled population ranging from 6 to 80 percent depending on
the specific symptom [10-13] and are also found in individuals with
anxiety [14], depression [15], PTSD [16], and pain [17-18]. In addition,
TBI is commonly diagnosed using neuropsychological assessments, but
interpretation of such assessment results can be confounded by the 5 to
85 percent incidence of false positive neuropsychological findings in
nondisabled populations (depending on the number of tests and the cutoff
level for identifying positive findings [19]).

Using the most common definitions of severity, a 2009 Institute of
Medicine study considered over 30,000 published studies and found an
association between moderate to severe TBI and neurocognitive deficits,
as well as problems with long-term employment and social relationships.
However, no clear association was found between mild TBI and objectively
measured neurocognitive deficits or long-term employment, social
relationships, and ability to live independently [2].

Although it is important to consider the multiple factors and
complex issues related to accurately identifying and diagnosing TBI, it
is also important to provide assistance to military servicemembers and
veterans who experience functional difficulties. It is important that
the VA provide resources to improve veterans' ability to function,
regardless of the relative contribution of TBI, anxiety, depression,
PTSD, sleep disorder, pain, substance abuse, or other factors
confounding diagnosis. Targeted interventions to improve specific areas
of difficulty, especially difficulties in community and vocational
participation, may be more important than diagnostic categorization.

It is important that interventions designed to improve
veterans' social and vocational participation be studied using
valid, reliable, and sensitive measures. One set of particularly
relevant measures that can help inform the rehabilitation process
involve measuring how successful individuals are in participating in
usual social role activities, i.e., working; engaging in leisure and
recreational activities with others; and being part of family,
neighborhood, and community interactions. Precise and comprehensive
measurement of rehabilitation outcomes related to participation is
needed to meaningfully evaluate and compare the results of different
rehabilitation interventions designed to improve the lives of veterans
with known or suspected TBI.

Therefore, this article considers the issues involved in measuring
rehabilitation outcomes regarding social participation in veterans with
possible, probable, and confirmed TBI. Specifically, we will--

Discuss conceptual models of participation.

* Review participation subdomains and their instruments of
measurement.

* Identify current research issues and needs related to measurement
of participation.

* Make suggestions for the future development of participation
measures.

CONCEPTUALIZING PARTICIPATION

Medical advances have led to more veterans and military personnel
surviving acute injury and illness and then living with chronic health
conditions. This creates a need for conceptual models to understand
disablement. In the conceptual model of the World Health Organization
International Classification of Functioning, Disability, and Health
(ICF) [20], rehabilitation outcomes can be considered in a three
categories. "Body Functions and Structures" refers to the
physical level of body structures and their associated functions.
"Activities" occurs at the task level and involves such things
as feeding, dressing, shopping, and operating a motor vehicle.
"Participation" occurs at the societal level and is an
interaction between the person and the environment in social roles,
involving such things as being a worker, student, friend, spouse,
parent, or citizen. While rehabilitation interventions to improve body
functions and structures and activities are certainly important, it is
participation that is most strongly linked to perceived quality of life.
However, participation in social role activities is challenging to
conceptualize and measure.

DEFINING PARTICIPATION

The ICF was the first model of disability to use the term
participation to refer to "involvement in life situations,"
but the concept of participation as involvement at the societal level
has appeared in all prior models of disability. For example, earlier
models used different terms than participation, including
"handicap" to indicate a disadvantage in society [21] and
"disability" to indicate problems with social role fulfillment
[22-24]. Although participation is a useful term to describe involvement
in family, community, and work roles, the ICF does not operationally
define participation in a way that distinguishes it from other concepts
such as activity and quality of life.

It is important to conceptually distinguish participation from
activity. As Whiteneck and Dijkers state, "activities are the
physical and cognitive tasks performed by individuals, while
participation is social role performance as a member of society"
[25; p. 24]. The ICF has been criticized for not adequately
differentiating participation from activity (at the person level) either
definitionally or in its single taxonomy of activity and participation
category codes [26-27].

Measures of participation are also difficult to distinguish from
measures of global life satisfaction such as quality of life [26]. In
contrast to the multidimensional health-related quality of life
construct [27], unidimensional quality of life measures evaluate general
wellbeing [28-29]. It is unclear whether subjective measures of
one's satisfaction with participation differ from subjective
judgments of well-being, which have been conceptualized as encompassing
eudemonic concepts such as purpose in life, personal growth, positive
relations with others, environmental mastery, self-acceptance, and
autonomy, as well as hedonic concepts such as happiness and life
satisfaction [30].

The ICF also does not clearly conceptualize how the interaction
between the person, the task, and the environment affects participation.
It is important to recognize that disability is a
person-task-environment interaction arising from the individual's
condition, the task in which they are engaged, and the environment in
which they engage with the task. For example, wheelchair users are less
disabled in communication tasks than in mobility tasks, less disabled in
physical environments with paved sidewalks and ramps than in physical
environments without such structures, and less disabled in social
environments with acceptance of variations in body functions and
structures than in social environments without such acceptance.
Therefore, participation is affected by aspects of an individual's
physical condition; motor and cognitive functioning; availability and
use of assistive devices; and the physical, social, and public-resource
environments in which they live.

In addition, we may need to expand definitions of participation to
include some unexplored areas that could be important from a conceptual
standpoint. Attention has not been given to the concept of negative
participation, wherein individuals engage in antisocial or illegal
interpersonal activities. Cyberparticipation, wherein individuals
interact without direct or even real-time contact with others, is
beginning to be incorporated into concepts of participation.
Hyperparticipation, wherein individuals engage in greater amounts of
interpersonal activities than they desire (when family, school,
community, and work demands exceed their preferences), has also not been
discussed in models of participation.

In summary, a clear and commonly accepted definition of
participation, distinct from activity and quality of life, is needed to
develop operational definitions and measurement instruments [25]. The
field of rehabilitation outcome assessment could also be enhanced by
more explicit incorporation of person-task-environment interactions into
these assessments. Inclusion of conceptual variations on participation,
such as negative participation or overparticipation, may also be
helpful.

MEASURING PARTICIPATION

In addition to conceptual clarification, improving the practical
enumeration of types of participation (distinct from activity and
quality of life) is also needed to advance the field of rehabilitation
outcome assessment [25]. As with the overall definition of
participation, agreement on the key subdomains of participation and
their measurement would be helpful. Whiteneck and Dijkers discuss that
participation can be measured using objective indices such as marital
and employment status, counts of social activities engaged in, and
inventories of common social activities [25]. These objective approaches
have been criticized as neglecting important individual variation,
especially with respect to how people with disabilities may prefer to
participate and how as a group, they may differ in important ways from
the nondisabled population upon which such measures are typically based.
It is not clear that participation is best measured by counting the
number of social engagements. Participation may include issues related
to amount, but people pick and choose their participation according to
preferences and perceived importance and difficulty, and thus the
subdomains are not hierarchical in nature (one type of activity does not
necessarily precede or follow another) [25]. Optimal participation,
rather than maximal participation, may be most important, involving the
perceived characteristics of those interactions (preference, importance,
and difficulty) [25].

Measuring participation that is specific to individuals with TBI is
also complex. First, individuals may have mild, moderate, or severe
injuries, and their specific injuries may result in different types of
disabilities. Second, we must consider the stage and trajectory of
recovery during which assessments are made. Third, although this
population is heterogeneous, some types of impairment frequently occur
that may directly affect a person's ability to reliably and
accurately communicate their thoughts and behaviors. These include
deficits in motor function, thinking and memory, communication and
social pragmatics, affective self-regulation, and accurate awareness of
self and others, which may compromise the validity of self-report
measures with this population [31-32]. Fourth, some participation
measures are completed by knowledgeable caregivers, and the degree to
which these reports may or may not agree with the person's own
report varies according to the type and degree of injury and the type of
participation measured [33-34]. Despite these difficulties, valid,
reliable, and sensitive outcome measures are needed that can help inform
the rehabilitation process by examining how successful individuals with
TBI are in returning to their families, communities, and work and social
involvements. This article discusses existing and developing instruments
for measuring participation in persons with TBI in relation to these
issues.

ESTABLISHED ASSESSMENT TOOLS

Although a number of different assessment tools have been developed
to assess participation in individuals with a variety of disabilities,
the majority of these are generic and not specific to persons with TBI.
Fortunately, recent measurement developments specifically target the
assessment of TBI-related participation issues. This article does not
attempt to provide a systematic or exhaustive review of all assessment
tools for measuring participation; rather, it discusses assessment tools
that have been specifically developed to evaluate participation for
persons with TBI.

One of the first assessment tools developed to examine
participation was the Community Integration Questionnaire (CIQ), which
includes an objective measure of participation in TBI samples (type and
frequency of activities). The complementary development of the
Participation Objective-Participation Subjective Scale (POPS) and the
Mayo-Portland Adaptability Inventory (MPAI) provides subjective
assessment of participation in TBI (amount of assistance needed). This
development work was further extended by the Participation Assessed with
Recombined Tools (PART), which takes items from each of these measures
(CIQ, POPS, MPAI) as well as the Craig Handicap Assessment and Reporting
Technique (CHART), to develop a more sensitive tool appropriate for use
in TBI.

Community Integration Questionnaire

The CIQ is a 15-item questionnaire developed to assess three
domains of community participation: home integration (4 items involving
household chores and child care), social integration (8 items involving
leisure and social networks), and productivity (3 items involving work
and school or volunteer participation) [35]. The items in the home
integration and social integration subscales are rated for levels of
independence in participation, the frequency of participation, and if
social interaction is involved, with whom the individual participates in
the activity. For the productivity subscale, the level of participation
is rated on the hourly amount of participation (full- vs part-time
participation in school or work) and the frequency of participation. The
questionnaire yields a total score and three subscale scores, with
higher scores representing higher levels of community integration. The
CIQ can be conducted in person and over the telephone and is designed
for use with the individual and/or a significant other.

The CIQ is the most widely used community outcome measure in TBI
rehabilitation [36]. Its strengths include brevity [36-37], orthogonal
subscales [36], and high test-retest reliability [35]. The CIQ was able
to discriminate individuals with TBI from nondisabled individuals and
also showed differentiation of scores in a TBI sample grouped according
to living situation (e.g., independent living, living with supports,
institutional setting) [35].

However, a number of critiques of the CIQ exist. First, the
development of the instrument was based on principal components analysis
of data from a sample of 49 individuals with TBI, which may have been
too small to provide adequate statistical power. Second, although
subsequent replication of the analysis verified the factor structure,
this replication did not include each of the original 47 items and
indicated lack of fit for two items (shopping and child care) [36,38].
Third, interrater reliability was initially assessed to be acceptable
[35], but later studies using the more accurate intraclass correlation
coefficient produced less robust results, especially for the social
integration and productivity scales [38-39]. Fourth, the CIQ does not
correlate highly with other measures of participation and/or disability
and thus may represent measurement of a unique domain of participation
or may not assess some relevant constructs [40-41]. Fifth, an
individual's score can be adversely affected by their level of
premorbid participation (e.g., if they never did household chores), need
for less supervision, and/or availability of the activity or need for
participation in the activity (e.g., child care) [36,38,42]. Sixth,
demographic factors and cultural values can influence the findings, but
no controls are included for these effects in scoring or normative
development [4347]. Seventh, although the sensitivity of this assessment
tool's ability to distinguish individuals with and without
disability is well established, it is less able to detect change as the
result of an intervention [40]. Finally, the priorities of the
individual are not included in the CIQ, and critiques have been directed
at the lack of consideration of the relevance of specific areas of
participation to certain TBI stakeholders (e.g., patients, families,
healthcare professionals, employers) [48].

Participation Objective-Participation Subjective Scale

The POPS was developed to prioritize the preferences and goals of
the individual with TBI and to map more closely to the ICF [26]. The
POPS is a 26-item self-report assessment tool evolved from a research
measure with data gathered from 454 individuals with TBI in the
community and 126 nondisabled individuals. It includes both an objective
(participation objective: frequency or duration of engagement) and a
subjective measure (participation subjective: importance of activity and
satisfaction with level of engagement) of participation. Areas of
participation are organized into five subscales that were conceptually
derived and conform to ICF categorization: domestic life; interpersonal
interactions and relationships; major life areas; transportation; and
community, recreational, and civic life. The participation objective
portion of the questionnaire quantifies participation as proportion of
responsibility, number of hours, or frequency of participation,
depending on the area of life measured. The participation subjective
portion quantifies the importance of the activity to the individual and
the desire for change in the level of participation. The two subscales
are summed into weighted averages, either using the mean ratings of the
standardization sample (participation objective) or using the importance
rating of the individual (participation subjective).

The test-retest reliability coefficients for the total scores were
adequate (intraclass correlation coefficient of 0.75 and 0.80,
respectively, for the participation objective and participation
subjective total scores); however, the range for the subscale scores was
more variable, with weaker reliability for the transportation and
community, recreational, and civic life subscales (0.28 and 0.37,
respectively) [26]. The subscales appear to be orthogonal on the
participation objective dimensions, indicating that the types of
activity are different, but share correlations on the participation
subjective dimension, indicating a coherent measurement of value.

The authors compared the scores of individuals with TBI with those
without disability and found that the ratings of the importance of
various activities did not significantly differ between the groups [26].
The authors compared the scores of individuals with mild TBI with those
with moderate to severe TBI and found that level of participation did
not significantly differ, but that satisfaction with participation was
lower for the individuals with mild TBI [26].

To date, the literature has reported no validation of the POPS
using other instruments of participation, and this remains a major
limitation. In addition, although the authors note that environmental
factors could affect the ratings of participation and/or satisfaction,
this potential confound is not included in the measure as a factor that
affects level of participation. In sum, while the POPS holds some
promise, further evaluation is needed to determine whether it is valid
and reliable in outcome assessment of participation in rehabilitation
trials.

Participation Assessed with Recombined Tools

The PART represents an attempt to select the best items from
existing instruments of participation [49-50]: the second edition of the
CIQ [51], the POPS [26], and the CHART [52]. Items from these
instruments were merged into a single instrument and administered to a
sample of 400 individuals with TBI at 8 of the 16 Federal TBI Model
Systems programs as they crossed their 1st, 2nd, 5th, 10th, and 15th
year anniversaries of injury. Using a combination of factor analysis,
Rasch analysis, and content analysis, the authors identified 24 items
that formed a new scale (PART) of participation (being productive,
socially integrated, and engaged in community life) demonstrating good
psychometric properties [49]. The authors selected all 24 PART items to
measure participation objectively (hours spent in productive activities,
frequency of involvement in social and community aspects of
participation, etc.), but they also identified the need for subjective
measures of participation, and a subjective tool is currently under
development. The PART is limited by the limitations of the measures it
incorporates because it did not include the validation of new items.

The PART correlates strongly with other measures of participation
and with measures of impairment, physical and cognitive functional
performance, and satisfaction. Specifically, the PART demonstrates
significant correlations with the MPAI 8-Item Participation Index
(M2PI), the Cognitive Functional Independence Measure, the Motor
Functional Independence Measure, the Supervision Rating Scale, the
Glasgow Outcome ScaleExtended, and the Dementia Rating Scale, indicating
that greater functional independence is associated with greater
participation [49]. In addition, the PART is significantly associated
with the Satisfaction with Life Scale [49]. Because of these strengths,
it was adopted as the measure of participation currently included in the
TBI Model Systems National Database [50].

Mayo-Portland Adaptability Inventory 8-Item Participation Index

The M2PI is an 8-item participation index taken from the 30-item
MPAI [53]. Currently in its fourth edition, the MPAI was designed and
validated to assess the overall level of disability across three
different domains: abilities, adjustment, and participation (the latter
comprising the 8 items of the M2PI). The M2PI covers eight domains of
social participation: initiation, social contact, leisure, self-care,
residence, transportation, employment, and money management. All items
use a 5-point rating scale ranging from 0 (no problem) to 4 (severe
problem) and were designed to reflect the World Health
Organization's distinction between impairment, activity, and
participation [54]. The M2PI was developed and validated in persons with
TBI [55] and demonstrated strong internal consistency, especially when
self-ratings for people with TBI were compared with proxy ratings
(support staff and significant others) [55-56]. It appears to have only
minimal floor and ceiling effects [57].

Because of the limited psychometric data supporting the M2PI, it is
important to provide a brief review of the psychometric properties of
the measure from which it was derived, the MPAI. The MPAI shows good to
excellent internal consistency (Cronbach [alpha] = 0.89, Rasch Person
Reliability = 0.88, Rasch Item Reliability = 0.99) [58]. Evidence for
its concurrent validity is supported by correlations with the Disability
Rating Scale [59] and the Rancho Los Amigos Cognitive Scale [60]. In
addition, the MPAI is a good predictor of vocational placement and
outcome [61-62] and community-based employment [63] in individuals with
TBI. The MPAI is also a good predictor of level of functioning, return
to employment, and independent living in TBI [64]. Given the importance
of community integration and vocational outcomes to individuals and
their families, and the significant Federal efforts to improve
vocational outcomes in veterans and persons with disability, the
correlation of the MPAI and M2PI with community employment may make
these especially important tools in rehabilitation outcome measurement.

EMERGING MEASURES OF PARTICIPATION

Although it is important to consider the conceptual differences
between participation and quality of life, participation is correlated
with quality of life, and therefore, quality of life measures can be
helpful in studying participation. As previously discussed, TBI
researchers have tended to use generic quality of life measures,
developed for use in the general population, which can lack the
sensitivity needed to detect meaningful differences in individuals with
TBI and often contain irrelevant material and omit issues that are
important to individuals with TBI.

For these reasons, the National Institute on Disability and
Rehabilitation Research (NIDRR) has prioritized research that
"leads to the development of the next generation of valid and
reliable measures of health and functional status among people with
disabilities" [65] Such projects also have the support of the
National Institutes of Health (NIH), National Institute of Neurological
Disorders and Stroke, National Center for Medical Rehabilitation
Research, and the VA Rehabilitation Research and Development (RR&D)
Service. The development of valid and meaningful instruments that
measure health-related quality of life specific to individuals with TBI
is an important step in TBI outcomes research. Most recently, two
measurement initiatives are creating item banks examining social
participation using state-of-the-art measurement development approaches.
Specifically, the TBI-Quality of Life (TBI-QOL) and the
Polytrauma-Quality of Life (Polytrauma-QOL) are using item response
theory methodology to develop computer-adaptive tests of participation
in individuals with TBI.

Traumatic Brain Injury-Quality of Life

The TBI-QOL is currently being developed as a meaningful, relevant,
and psychometrically sound measure that provides comprehensive
assessment of health-related quality of life for persons with TBI [66].
Further, the TBI-QOL will allow for comparison of the health-related
quality of life of individuals with TBI with the health-related quality
of life of persons with other neurological conditions.

The TBI-QOL uses methodology employed by other NIH-funded,
larger-scale initiatives (e.g., http:// www.promis.org/ and
http://www.neuroQOL.org/). Specifically, focus groups were conducted
with a diverse sample of individuals with TBI, their caregivers, and
interdisciplinary teams of healthcare providers to discuss issues
related to quality of life. Major content areas were identified and
coded, including emotional health, cognitive functioning,
physical/medical health, sexual functioning, personality changes, and
(of interest to this article) social functioning. Item banks are under
development for social functioning that will include both social role
performance and social role satisfaction items related to leisure
functioning, interpersonal relationships, vocational functioning, and
independence/autonomy.

The TBI-QOL will provide a specialized outcome measure that
assesses the needs of individuals with TBI. It will evaluate areas of
functioning that are unique to TBI, plus include a number of items that
will allow for crossdisease comparison with other neurologically based
diseases.

Deployment-Related Traumatic Brain Injury/ Polytrauma-Quality of
Life

The VA RR&D Service grant program has funded a study to adapt
the TBI-QOL for use in the VA system with individuals with TBI. The VA
study uses a similar design as the TBI-QOL: new item banks will be
developed using veteran focus groups, item response theory analyses will
be performed to develop short forms, and ultimately, the Polytrauma-QOL
will be administered as a computer-adaptive testing (CAT) methodology.
The long-term goal of the Polytrauma-QOL is to develop a clinically
sensitive scale for clinical trials, program evaluation, and outcome
monitoring in clinical practice with individuals with deployment-related
TBI. Ultimately, the final product of this project--a conceptually
grounded, deployment-related TBI health-related quality of life
assessment tool--will be integrated with larger NIH- and NIDRR-sponsored
rehabilitation outcomes assessment projects to allow results obtained in
samples of military servicemembers with TBI to be directly compared with
samples of nonmilitary individuals with TBI and also to veterans and
nonveterans with other neurologic disorders.

Newer Areas of Participation

While some current measures of participation, such as the Community
Participation Indicators measure, include items such as communicating on
the telephone and by email as examples of social activity, future
participation measures will undoubtedly also include participation in
electronic social networking (e.g., Facebook and Twitter). Studies in
nondisabled populations suggest that using Facebook can enhance
"social capital," particularly for those with lower
self-esteem [67]. Although some studies suggest that the effect is small
in nondisabled college students [68], electronic social networking may
assume a more prominent role in the lives of people who are housebound
or whose "traditional" participation is restricted. Thus,
electronic social networking is likely to gain a place in the
armamentarium of participation measurement in medical rehabilitation
populations, including TBI.

RESEARCH METHODS AND GAPS

Similar to other areas of rehabilitation outcome measurement,
developing measures of participation for individuals with TBI faces
multiple challenges. In this section, we discuss limitations of existing
measurement development efforts and methods by which improved measures
of participation can be developed and tested. In particular, we will
discuss using qualitative methods and item response theory to guide
measurement development. We then turn to measurement issues specific to
the TBI population that present challenges for measurement development
and opportunities for research.

General Considerations in Measurement Development

The process of developing assessment tools measuring any domain or
construct involves developing items and rating scales and then
evaluating the function of these items and scales relative to a given
study population. Creation of test items should meet the criterion of
contemporary qualitative and quantitative methodologies. Guidelines from
the U.S. Food and Drug Administration (FDA) for the development of
Patient Reported Outcome for pharmaceutical labeling [69] may be a
useful framework for developing test items to measure aspects of
participation. Of particular relevance is the FDA requirement of
incorporating interviews or focus groups from a wide range of patients,
across a variety of severities and population characteristics (e.g.,
age, sex), into item generation process. Because of the broad scope of
participation, qualitative approaches such as focus groups may be
particularly useful in determining themes and content areas and could
potentially be used to generate item pools for new measurement
instruments.

State-of-the-science item-pool development strategies include
techniques such as binning and winnowing [70]. Binning involves the
systematic grouping of items according to specific subdomains. Winnowing
involves reducing item pools to a representative set of items. This
process involves consensus among item developers as to whether
particular items should be included or excluded based on operational
definitions of subdomains. Cognitive interviewing and debriefing
strategies are also becoming standard procedures for test item
development [71]. This approach involves presenting items to potential
respondents to obtain detailed information regarding item
interpretation. This may be particularly effective in ensuring that test
items are readable and understandable by individuals from different
ethnic and socioeconomic backgrounds.

Older measures of participation have used classical test theory as
the dominant framework for both instrument development and psychometric
evaluation. While classical test theory methodologies examine the
properties of the test as a whole, it is also necessary to look at the
function of the items and the scale used to rate item responses. Item
response theory examines the function of items relative to a
person's ability [72-73]. Classical test theory methods, such as
factor analysis, hierarchical linear modeling, structural equation
modeling, and cluster analysis, in combination with item response theory
methods, such as fit statistics, item difficulty calibrations, item
discrimination, tests of monotonicity (rating scale analysis), and
differential item functioning, are all important for test development.

The development and testing of the Activity and Participation
Measures for Post Acute Care and the development of the TBI-QOL are good
examples of this development method. The measures have been examined
with classical test theory and item response theory methods to address
questions related to uni- versus multidimensionality. First,
correlations are computed between the individual items and the total
scores (i.e., sum of the individual items within a subdomain), as well
as the total scores of other criterion measures, are used to determine
which items are retained and which items are eliminated. Item response
theory methods are then employed to calibrate the remaining test items
in preparation for building a CAT version. CAT allows evaluators to
administer item subsets that ease administrator and respondent burden,
while maintaining good psychometric properties.

Existing evidence largely supports the idea that scales measuring
major life domains, such as participation, can be constructed along a
dimension of more to less (e.g., more to less participation limitation
or participation satisfaction). Ultimately, however, a more complex
model may be needed to fully reflect the complexity of life
participation [74]. This is illustrated by recent efforts to develop
measures of social health [75]. The Patient-Reported Outcomes
Measurement Information System social domain workgroup used focus groups
and expert opinion (i.e., Delphi methods) to develop the content of a
social domain framework. The framework consisted of two primary
branches: social function and social relationships. Participation
ability and satisfaction, rather than participation frequency, were the
two subdomains selected under social function. Positively and negatively
worded test items to measure these two subdomains were obtained from
existing instruments and new items were developed to fill gaps.
Limitations in reaching a unidimensional structure and inconsistencies
in item-difficulty hierarchical ordering (such as more or less) suggest
that a unidimensional item response theory model may not be applicable
to measuring participation [25].

Traumatic Brain Injury-Specific Considerations

While the psychometric methods described are relevant to the
development of any type of measure, the development of participation
measures specific to TBI poses unique challenges. The reliance on
self-report causes characteristic challenges for research on TBI because
the reliability of self-report may be affected by TBI-specific cognitive
impairments such as difficulties in communication, memory, and awareness
of limitations [31-32]. The reliability of proxy report following TBI
also seems to vary systematically by the area of participation, with
activities related to economic productivity showing more robust
self-proxy report agreement compared with home and social activities
[33-34].

It is important to note that even instruments that use multiple and
complementary measurement methods and input from multiple stakeholders
are susceptible to biases. For example, in a recent study [33] of self-
versus proxy-report at 1 year post moderate to severe TBI using the
Community Participation Indicators measure [34], items pertaining to
economic and community activities showed high concordance. However,
specific activities that might be important for health studies showed
surprisingly low agreement (e.g., frequency of exercise outside the
home). Social activities, even those that might be objective or
observable (e.g., frequency of getting together with family and
friends), also showed surprisingly low agreement. Satisfaction with the
degree of participation showed low self-proxy reliability, although
proxies who spent time with participants every day had significantly
better congruence.

It is theoretically possible to bypass these problems with self-
and proxy-report by directly measuring the objective aspects of
participation through behavioral observations or by technologies such as
personal digital assistants (PDAs). Seekins et al. demonstrated the
measurement of direct behavioral observations using Ecological Momentary
Assessment. Ecological Momentary Assessment is a behavioral recording
technique that allows the participant to record specific data in
response to external triggers, such as an alarm, or internal events,
such as feeling irritated [76]. In a pilot study, people with
disabilities involved in vocational development were given PDAs and
asked to record data across a 9-month period. Data collected for 7
weeks, spaced across the study interval, included what the participant
was doing; where and with whom; whether there were barriers or
facilitators present; and how the participant felt, including level of
fulfillment reached by engaging in the activity. Results suggested that
high levels of connectedness and fulfillment occurred during employment,
seeking employment, and other community-based pursuits, with lower
levels for home activities (either home management or leisure
activities). The context of an activity (especially participation with
others outside the home) was more strongly related to fulfillment than
the actual content of the activity.

In summary, researchers face a number of challenges in developing
new instruments and refining existing instruments to measure
participation outcomes in TBI. While these challenges relate to
measuring participation in general, additional complexities exist that
are unique and specific to TBI. Given that TBI rehabilitation aims to
enhance participation, the measurement of participation after TBI is
important, and emerging methods may be useful in producing effective
measures of participation. Suggestions to advance the field of measuring
participation in persons with TBI are discussed later.

MOVING THE FIELD FORWARD

Based on this review of currently available and emerging
instruments and issues related to the measurement of participation, we
identified two avenues for advancing the field of participation
measurement in persons with TBI. The focus of this article is on
veterans with TBI; however, this does not limit the applicability of
these recommendations to the VA alone, and where possible, extension of
these recommendations to non-VA settings is discussed. First, we
describe suggestions to facilitate the immediate implementation of
participation measurement in TBI clinical practice and TBI
rehabilitation research. Second, we describe recommendations for future
research initiatives specific to participation in persons with TBI.

Immediate Implementation Strategies

The VA has been a leader in implementing evidence-based healthcare.
In accordance with these efforts, we describe suggestions to encourage
adoption and use of participation measures in VA TBI clinical programs
and research initiatives. These suggestions capitalize on the expertise
and resources that already exist in the VA and encourage dialog between
the various clinical programs and research services to enhance
state-of-the-science implementation.

Basic Research: Develop Evidence-based Synthesis Program Priority

We suggest that the VA, in conjunction with other Federal agencies
and academic and clinical centers of excellence, conduct evidence-based
reviews of the psychometric properties (i.e., reliability, validity,
precision) of existing instruments for measuring participation specific
to persons with TBI. The evidence-based review summary suggested here
should clearly delineate the psychometric properties and areas of
measurement for each instrument and the evidence for using the
instruments with TBI. The review should provide evidence-based criteria
that can be used by readers to guide the selection of existing
participation measures for use in TBI patient outcome measurement. This
review would provide a basis for identifying which existing measures
should be refined and which areas of participation measurement need
further development. The VA's existing Evidence-based Synthesis
Program, funded by the Health Services Research and Development Service
(http:// www.hsrd.research.va.gov/publications/esp/), could conduct this
evidence-based review in cooperation with other public and private
partners. Coordinating existing expertise in rehabilitation will ensure
that the systematic review of the literature is (1) relevant to quality
healthcare services for veterans, (2) evidence based, and (3) compatible
with ongoing investigations of TBI diagnosis and treatment already
funded by the VA and other Federal agencies.

Clinical Integration: Develop a Rehabilitation Medicine Assistant

Instruments that measure participation are important in assessing
TBI rehabilitation outcomes. Coordination of VA clinical practice groups
involved in TBI care with the VA Polytrauma Network teams is critical
for standardizing participation measurement in clinical rehabilitation
treatment protocols and to the use of participation measures in tracking
clinical rehabilitation outcomes. We suggest that a VA Rehabilitation
Medicine Assistant be developed, similar to the Mental Health Assistant,
as part of the Clinical Patient Record System. The Rehabilitation
Medicine Assistant would be based on an evidence-based review and
periodically modified using feedback from subject-matter experts in TBI
rehabilitation and participation measurement. It would make
participation measurement instruments readily available to clinicians
and researchers, which would facilitate the integration of these into
clinical care planning and treatment goal setting. This would provide
important information about the real-world rehabilitation outcomes that
are most important to patients and families.

In order to examine the extent to which participation measurement
provides useful feedback to rehabilitation teams and improves treatment
outcomes for persons with TBI, we recommend that a VA Quality
Enhancement Research Initiative priority be established to examine the
performance of participation measures identified in this article
(http://www.queri.research.va.gov/). These participation measures could
be examined in different clinical settings to identify their utility in
individual patient treatment planning and the relationship of
participation measures to healthcare outcomes. This research is vital to
the development of future clinical translation trials helping to
reintegrate veterans into their homes, communities, and social roles.

Future Research Priorities

Public policy and legislative efforts recognize the importance of
work and social participation for veterans with TBI. These efforts
include creating stable housing programs to ensure safe and adequate
accommodations for veterans with disabilities, providing healthcare
services to optimize rehabilitation outcomes and social participation,
and creating job opportunities and incentives for employers to hire
veterans. However, reliable, valid, and relevant measures of the
effectiveness of these programs should be improved. Such research can be
used to improve care, inform public policy, and guide legislative
efforts.

In this article, we identified gaps that could be successfully
addressed through organized research efforts. The primary areas for
future research are (1) developing a solid theoretical base upon which
to build measurement efforts in this area, (2) refining existing
measurement instruments to incorporate issues specific to TBI
rehabilitation with veterans, and (3) developing individual
participation profiles to understand personal preferences and guide
clinical rehabilitation goal setting and treatment planning that is
relevant to specific individuals. Within these efforts, it is important
to consider what constitutes meaningful change for the individual and
what effect participation has on individuals' well-being and
quality of life. Emphasis on measurement of rehabilitation outcomes that
are based in the real-world experience of the individual and that
complement other TBI rehabilitation outcomes will be valuable for our
nation's veterans and would be potentially generalizable to
civilians and other disability populations. Developing these
methodologies and measures will contribute substantially to the
improvement of intervention efforts to aid our nation's veterans
and are critical to advancing the science of measuring participation for
persons with TBI.

JRRD at a Glance

The Department of Veteran Affairs (VA) has devoted substantial
resources to the rehabilitation of veterans with traumatic brain injury
(TBI). One of the most important rehabilitation outcomes is
participation in community and work activities, which is strongly linked
to quality of life. This article discusses the concept of participation,
existing ways to measure participation, and research issues in measuring
participation. Suggestions are made to facilitate the use of
participation measurement in TBI clinical practice and rehabilitation
research and for future VA research funding for measuring participation
in veterans with TBI.

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